Vick made his comments on FS1's "Speak For Yourself."
"First thing we've got to get Colin to do is cut his hair," Vick said. "Listen, I'm not up here to try to be politically correct. Even if he puts cornrows in there, I don't think he should represent himself in that way in terms of just the hairstyle. Just go clean-cut. You know, why not? You're already dealing with a lot of controversy surrounding this issue. The most important thing that he needs to do is just try to be presentable."
Kaepernick, 29, is a free-agent quarterback. He spent his first six seasons with the San Francisco 49ers. He was in the spotlight last season for his decision to kneel during the national anthem as a way of protesting social injustice. He sported an Afro during the season, but his hair was in braids during a recent trip to Africa.
Vick issued a statement Tuesday to clarify that what he said "was not in malice."
"Colin Kaepernick's hair has nothing to do with him not being on a NFL roster right now," his statement said. "Let's be clear! I wish only the best for Colin. I stand by what I've said about him being signed at some point this season to help a NFL club. I think he is a great kid who has a bright future and I'm looking forward to seeing him on the field again. Trust and believe what I said was not in malice."
Shortly after, Kaepernick made an apparent response to Vick's comments by tweeting out the definition of Stockholm Syndrome.
Vick, 37, spent 13 seasons as an NFL quarterback. His career was interrupted by a 21-month federal prison sentence for running a dogfighting ring. He said Monday that he was given advice during his career that he needed to change his image, but he "didn't listen until the end, until I was going through the turmoil and the hardships."
"I just think perception and image is everything. This is not the Colin Kaepernick that we've known since he entered the National Football League," he said. "I'm just going off my personal experiences. Listen, I love the guy to death. But I want him to also succeed on and off the field. This has to be a start for him."
He said he would give Kaepernick this same advice if he was talking directly with him.
Vick said Kaepernick's image isn't the primary reason he's not signed but that it's "because of the last two seasons and not being as productive."
"The reason he's not playing has nothing to do with the national anthem. It's more solely on his play. But, yeah, everything takes precedent, in terms of image, perception," he added.
Vick said "it's not about selling out."
"When you're good, and you're playing great, then you're going to be wanted. People are going to want to sign you, going to want to see you play," he said.
Kaepernick has remained unsigned since opting out of his contract in March. Aside from a meeting with the Seattle Seahawks, he has drawn little interest from NFL teams.